Electronic cycle computer



April 5, 1960 J. l.. BARKER ELECTRONIC CYCLE COMPUTER 5 Sheets-Sheet 1Filed Sept. 21. 1954 April 5, 1960 J. L.. BARKl-:R

ELECTRONIC CYCLE COMPUTER NERE 5 Sheets-Sheet 2 m .Sk m. .Sl m

April 5, 1960 J. L. BARKl-:R

ELECTRONIC CYCLE COMPUTER 5 Sheets-Sheet 5 Filed Sept. 21, 1954 April 5,1960. L. BARKER ELECTRONIC cYcLE: COMPUTER da@ ATTORNEY April 5, 1960 J.L. BARKER ELECTRONIC CYCLE COMPUTER 5 Sheets-Sheet 5 Filed Sept. 21.1954 a s E um@ E msm.

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ATTORNEY nited States Patent O faice ELECTRONIC CYCLE COMPUTER John L.Barker, Norwalk, Conn., assignor to Eastern Industries, Incorporated,East Norwalk, Conn., a corporation of Delaware Application September 21,1954, Serial No. 457,437

27 Claims. (Cl. 340-41) This invention relates to an electronic circuitfor accepting input impulses of variable time length' and variable timespacing, and for controlling the actuation of one of a plurality ofutilization devices selectively in 'accordance with measures of thedensity of the received pulses with respect to time. More particularly,the invention relates to an electronic system for the control ofvehicular or comparable types of traffic wherein it is desired tocontrol the ultimate rate of ow of the traffic in accordance with, andproportionally to, the average rate at which such traffic is presentedto traic-detecting devices.

Heretofore, a v-ariety of devices have been proposed to facilitate theow of traic along highways, particularly those that pass throughcongested areas in which it is necessary periodically to provide forright-of-way for vehicles on side streets and at highway intersections.For example, in my Patent No. 2,288,601, issued July 7, 1942, there isdisclosed an integrated trafiic control system whereby one or more traiclights arranged at intersections may be controlled to function in any ofa variety of different timing periods in accordance with the volume oftraflic flowing on the highway. As outlined in this patent, it has beenfound that more efficient use of existing highway facilities canreadilybe obtained by varying the light-timing cycle controlling thetraic itself. For example, if the traffic on the main road is relativelylight, the trafc lights at each intersection may be placed under thecontrol of associated local controllers which may be of the full orsemi-traffic-actuated type in which the transfer of right-of-way to oneroad from another to initiate a right-of-way signal is made responsiveto traflic `actuation of a traiiic detector in such one road, or may beof such other type of local control as may be desirable. As traicincreases, however, it is necessary to place the individual intersectioncontrollers under a coordinated master control system whereby trafliclights at successive intersections may be operated in accordance with anoverall plan to provide the most eicient use of the highway. To this endit is essential that the master control system provide a variety ofdifferently timed cycles of operation for th-e several intersectioncontrollers. In each instance, the timing cycle selected is one toprovide Vfor the freest possible flow of traliic on the main highway inaccordance with the density of traic known to exist on such highway and,at the same time, to avoid undue interference with the movement of sideroad traic that is attempting to cross or enter the highway.

In the arrangement of the master controller disclosed in theabove-mentioned patent, the density of the traiic on the main highway isdetermined over pre-established sampling periods, preferably ofsix-minute duration, and

the master controller timing cycles are actuated in accoi-.dance withthe density observed during suchperiods. Specifically, the apparatusincludes a trafc signal cycle selecting apparatus for control of amaster controller for a seriesof individual intersection traiiicsignalvcontrollers 2,932,003 Patented Apr. 5, 1960 along a road andhaving a number of different traic signal cycles including one minimumcycle providing independent control of the individual controllersresponsive only to traic'actuation of a traic detector at the individualintersections, a number of other cycles of successively longer timelengths providing coordinated control of the several individualcontrollers to have accord of right-ofway proceed progressively alongthe road at successively lower traic speeds, and a cycle of maximumlength providing synchronized coordinated control of the individualcontrollers for substantially simultaneous accord of right of way. Thecycle-selecting apparatus, when operating in any given cycle, iscontrolled by a vehicle-counting device to maintain the existing cyclein the event the density of traic on the highway remains unchanged or toshift to a higher or lower'cycle, respectively, depending upon anincrease or decrease in vehicle traic on the highway. l

The basic concepts of the traffic control devices disclosed in thepatent have proved extremely useful in most cases of highway trafliccontrol and are embodied in many control systems in current use.However, the substantial increases in operating speeds of vehicles andin the numbers of vehicles using our highways during recent years haveimposed limitations on the use of the relay circuits disclosed in thepatent. Furthermore, although the effectiveness of such systems can beimproved by increasing the number of detectors used to determine thevolume of traflic owing on a highway, it has been found that an increasein the number of vehicle-counting devices imposes a further load on therelay circuits of the patent. In addition, at the time the patentedstructure was developed, it was believed that in the general applicationof traliic control it could be assumed that traffic volume wouldincrease or decrease gradually over any given period and that theconcept of step-by-step changes in traic light cycling was the mosteffective method of control for most instances. However, it has beenfound that the use of progressive changes to'step through successivecycles to eflzect faster or slower movement of traffic is not the mostpractical method under all operating conditions. For example, if it beassumed that the traflic light system inthe vicinity of a largeindustrial plant is operating at its lowest cycle immediately prior toquitting time, a progression of live cycling periods would be requiredbefore the system could be raised to its highest or most effectiveoperating cycle. If the system employed a six-minute sampling period,such a procedure would require 30 minutes to complete. Obviously, thistype of control does not provide for the most efficient use of the roadadjacent the plant during the periods of the day that a large number ofemployees are arriving or leaving by car. Finally, traictstudies haveshown that'traflic patterns for a given locality vary as a result ofmany constantly changing factors and that the several change over pointsat which the master controller effects selection of the severaloperating cycles should be capable of Vrapid and convenient adjustmentto permit a traffic engineer or operator to adapt the system to any setof conditions that assapos f l In addition the output of this countingcircuit is employed to provide a Vdivided or proportionately reducedconstant pulse unit output that is fed into separate integratingcircuits whereby it is possible to obtain aninstantan'eous measure andindication of the traffic passing a given point or points over arelatively `short period of time, as well as to obtain an average traicdensity measurer'n'ent and indication yover alonger period 'of timewhich may be employed Aas a sampling period. Both of such measures maybe indicated selectively for the immediate guidance of the trafficengineer operating the system, whereas the average density measurementis employed jdirectly to effect the selection vof successive operatingleads of the master traffic 'controller and may be employed to actuate a`recording device whereby the information relating to trafiic densitiesmay beA stored for future study. l Finally, the output of the averagedensity-measuring circuit is applied to a cycle computer network thatiseliectiye to select the proper Ioperating cycle on which the 'trafficsignals should be functioning in accordance with the density of trafficthen being detected: l

Although in some respects the t'er'ms traiiic density" and trarne volumeare round in the Y'art tonlraye ditjferent meanings as the number of`yehicl es p cr `unit distanc'e along a road and 'as the number ofvehicles 'passing a given point per unit of time respectively asindicated for example at pages 477 and 481 'in the Trafiic EngineeringHandbook, vsecond edition, published 1950 by the Institute of TrafiicEngineers, these two terms are Jused interchangeably in the presentapplication as re- 'ferring generally to the number of vehicles passinga given point per unit time at `one or more locations as the case mayvbe in the context. vIn general, the invention provides a trafiicintegrating control circuit in which traffic counts may be detected A'atvarious points on highways or feeder lanes, thatis detectorsmay beplaced in vindividual lanes of a highway or in feeder lanes. The circuitof this invention totalizes the information received from the variousdetectors, and in accordance with predetermined conditions set in thecircuit bythe operator, actuates the different output circuits.Preferably these various output circuits control tratric mechanisms,such as synchronized traic controllers which may be so adapted Aas tovary the synchronization of the lines in accordance with the density'ofthe traiiic onthe routes being analyzed.

An example of this operation would be 'a system *in which the trafficcontrolled mechanisms would be adapted to provide different cycles ofoperation Von 'a series of synchronized traffic lines according to theload upon the lanes of a main highway plus those of 'an important feed'-erroad. A particular advantage of this Vinvention is that 'it providesfor switching from one to another of its output control circuitsactuating the traic control mech- `-anism's; in any sequence and thusavoids the delay often encountered in ,the former` step-wise switchingdevices vof the prior art. This is particularly important lin any cir-:cumstances where peak `loads occur suddenly such as at quitting time ina large industrial plant.

Additionally, this invention provides circuits which 'enable the mastercontrolling system to change from one to another of the alternativetratlic control circuits substantially within a single sampling periodwhen peak loads occur without yencountering the usual time period delayoften found in devices of this character.

Incorporated in the circuit of this invention are conltrols enabling theunit to have greater iiexibility than has previously been found in suchcircuits. Contributing tosuch iiexibility is the ability of thecircuit'selectively to detect one through four lanes of trafiic and tocompensate the parameters of the circuit accordingly when the number ofdetectors is varied. It allows for control of the various traiiicactuating mechanisms Yin accordance with tratiic densities which may bepresent `by the operator and additionally allows for the switching fromone t'raic actuating circuit to another at different trafic densitypercentages depending on whether the load is increasing or decreasing.This ability to control the transfer points individually provides fornot only greater flexibility but a more efiicient degree of control andwider permissive variations.

The principal object of this invention is to improve the flexibility andresponse time characteristics of traiicactuated control systems. Afurther object is to increase the accuracy of the determination ofdensities of traine and their respective assignment to provide trafiicsignal cycles.

A further object is to increase the acceptable total variation overwhich traic from the sampling detectors may be made to occupy the totalselected range. A further object is to simplify the adjustment of thesystem and the interpretation of the results provided by the systembythe provision 'of linear adjusting dials andfindi eating scales.

These and other objects are attained, in aprefe'rred form oftheinvention, 'as shown in the appended 'draw- `i'ngs, in which: y Fig. 1is va block 4diagram of the several components offtheinv'e'ntion;

Fig. 2 is a wiring diagram of 4the vehicle-detecting and waveshapinglcircuits of the invention;

Fig. 3 is a wiring Adiagram of the vehicle density averaging andindicating circuits;

Fig. 4 is a wiring diagram of the cycle computer;

Fig. 5v is ablock diagram indicating the mannerin kwhich Figs. 2, 3 and4 are combined to form a complete circuit diagram of the preferred formof the invention;

Fig. `6 is a front elevation of a control panel from which the severalcircuits of the invention may be op erated.

Pig. 7 is "a graph illustrating the operation of the invention asapplied to a traffic controlproblem.

Turning vto Fig. 1, the circuit Iof this invention yis there generallyshown in block diagram. As shown, the'circuit here ina'y be actuated byfour detectors identified as deI tectors 1 through 4. These detectorsare of any 'standard type Vsuch as pressure action actuated and are notper ise part of this invention. The respective detectors are connectedto individual pulse-forming circuits identified by the numerals 1, 2,13and l4. These circuits serve topro- ,vide a pulse 'output as a result ofthe signal sent to them Aby their respective detectors. Each pulseformer has its respective isolation diode as represented by box 5 inFig. '1, and pulse forme'rs 1, 2, 3 'and 4 are connected to theirrespective isolation diodes by leads 6, 7, 8 Iand 9 respectively. YTheisolation diodes have the purpose of segrelgating each ofthepulse-forming circuits from the remainder of the circuits of thisinvention. They also have included in their circuit neon indicatingmeans, to be described below, which will indicate to the operator which'ofthe various detectors is being operated. These neon indicating lightsare represented by numerals 11, 12, 13 and 14.

It will be understood that this invention may be adapted for use withmore or less than four detectors, if desirable, merely by adapting theprinciples herein set forth.

The pulse shaped output wave from the various isola- ,tion diodes 5 isconnected by lead v18 to pulse Shaper 19. There the signal is amplifiedand sharpened so that the output signal is clean. This output signal isconnected through lead 20 to flip-flop circuit 21 of substantiallyconventional well known design. The output of this circuit is a squarewave having van output of one cycle for every two input: pulses, thusfurnishing one cycle of output for each 'vehicle Which passes over agiven detectorfsince two lpulses ywill be created by eachtwo-axlevehicle) For pur- *poses to be later described,'the flip-flop circuit isadapted to provide a full cycle of output'for every input vpulsewhenbutaesingle'detectorfis in use. This moditication of operation iseffected through a resistance connection in lane switch 22 connected toip-op circuit 21 through lead 23.

The output of flip-flop circuit 21 is fed into pulse-Shaper 25 throughlead 26. In this circuit, the square wave is differentiated to provide apositive pulse; and the positive pulse amplied, producing an output wave180 out of phase so that the output of the pulse shaper 25 is a negativepulse. It will be noted that this output represents one negative pulsefor every full cycle of operation of the flipflop circuit 21.

Connected to the pulse shaper 2S to receive the negative pulse output isa one-shot timed multi-vibrator 27 connected to the pulse shaper 25through lead 28. This multi-vibrator is adapted to generate a full cyclesquare wave of predetermined amplitude and adjustable duration for eachnegative impulse received. The duration of the square wave output issubject to two controls by the operator of the device. The first is the100% density control 29 connected to multi-vibrator 27 through lead 30.This density control in effect varies the timing of the multivibrator bymeans of a potentiometer varying the applied voltage, to be laterdescribed. Its purpose is to enable the loperator to set the circuit forthe 100% density by assigning the approximate maximum level of traflicof the particular highway in question to the 100% point on the computerin accordance with ratings previously determined by traic engineers. Aswill be later described, this is an important setting since the circuitis adapted for alternative distribution of the traic control circuitsbeing regulated in accordance with percentages of normal trafficdensity.

The other setting for the multi-vibrator 27 is through lane switch 22,connected to the multi-vibrator by lead 31. This lane switch hasincorporated within itself capacitors of values bearing relationshipsinversely proportional to the numbers of detectors in the circuit at agiven time, thus in effect serving to halve the time of themultivibrator cycle when the number of lanes is double and so maintainproportionate trac density percentages in the output circuits andassociated meters or recorders. This lane switch, however, does notdifferentiate between the use of one and -two detectors in the preferredform due to the compensation previously mentioned which is applied bythelane switch circuit 22 to the flip-flop circuit 21.

As will be seen, the output of multi-vibrator 27 then is a square waveof uniform and constant amplitude and of predetermined and calibratedduration. One cycle of output is had for each vinput impulse receivedfrom any one of the detectors in the circuit -at a given time.

The square wave output from multi-vibrator 27 is connected through lead33 to charging circuit switch 34. This switch, in eifect, emphasizes andshapes the output wave so that the output from switch 34 is a squarewave of precise amplitude and duration as timed by the multivibratorcircuit. This output wave is impressed upon charge circuit 35 throughlead 36. Charge circuit 35 controls the unit charge applied to acumulative charge condenser for each pulse from switch 34 so that thetotal charge on this condenser will be linear with respect to the totalnumber of pulses, for a given adjustment of output pulse length of themulti-vibrator circuit. L

The charge circuit 35 is coupled through lead37 to instantaneous densitycircuit 38. This latter circuit serves to sum up the charges impressedupon the charging circuit over a specific period of time in accordancewith the RC constant of the circuit, this time period preferably being20 seconds. Accordingly, output voltage can be obtained from theinstantaneous density circuit 38 which substantially represents thedensity of the traiiic being measured at agiven time. This measurementcan be shown on a meter connected in the instantaneous indicating andmeas uring circuit 39, coupled to the output of instantaneous densitycircuit 38 through lead 40. The instantaneous indicating and measuringcircuit 39 is alsoY coupled through lead 42 to the up-down averagingtime circuit 43. This circuit has a second RC constant of longer andvariable duration vordinarily having periods from one to nine minutes.

The output of the averaging time circuit 43 is fed into the averagingindicating measuring circuit 44 through line 45, for amplification andcoupling to both the metering and control portions of the circuit.

The outputs of the instantaneous measuring circuit 39 and of the averagemeasuring circuit 44 pass through leads 46 and 47 respectively, toswitch 48 from which either one or the other may be connected to adensity meter 50 or a recorder 51. The meter 50 is used to show theoperator of the unit the density of the traic in the particular lanesbeing checked; and the recorder, for making a permanent record of samefor later analysis.

Lead 52 takes another portion of the output of the average indicatingmeasuring circuit and connects it to a distribution network composed ofa vseries of relay networks 53, 54, 55, 56 and 57. These units togetherlconstitute a cycle selecting computer and actuate relays,

so that any of the relays associated with circuits 53, 54,

55, 56 and S7 may be actuated according to the voltage on lead 52. Aswill be described below, only one of the output circuits from theserelay units will be connected a-t a given time. Associated with each oneof the units is an indicating neon light 58, 59,v 60, 61, 62 and 63,respectively, which serve to show the operator which one of the networksis in use ata given time.

The schematic circuit for the cycle computerof this invention is shownin Figs. 2, 3 and 4, which figures are interconnected as indicated inFig. 5.

Turning to these figures, the four individual detectors are coupled tothis cycle computer circuit in the lefthand portion of the drawing. Theincoming series of leads from the detectors are indicated by numerals70, 71,` 72 and 73. Since the four detectors are identical, only the onereached by the incoming leads 70 will be described. This will also applyto the subsequent pulse former circuits and isolation diode circuits. Aswitch 75 in line 70 may serve to connect the detector to the remainderof the circuit. One side of leads 70 pass through condenser 76 and theprimary of transformer 77 back to the other of leads 70. Connectedacross the primary of transformer 77 is another condenser 78. A chargeof 15 volts positive is placed upon condenser 76 from lead 79r which isconnected to the voltage divider circuit made ,upI

most detectors, the type of detector to be used with thisl circuit isone having a normally open circuit temporarily closed as a result of thepassage of a vehicle. This closing of the circuit, in effect, connectsleads 70 together, thu's allowing condenser 76 to discharge and passinga pulse of current through the primary of transformer 77. A resultingpulse will appear on the secondary of transformer 77 and pass throughseries resistors 85 and 86 to the grid of triode 87. Triode 87 and itsassociated circuit represents the pulse former circuit previouslydescribed. There is acomparable pulse former circuit for each de tectorand preferably its pulse former circuits will be made up by use of adouble triode of the 5965 type.

If'desired, the detectors may be connected to the remainder of thecircuit over standard telephone lines.

It is to be noted at this point that a power supply is available forfurnishing the necessary direct current voltages needed in the variousportions of the circuit. Since this is the conventional design, itwillnot be described. Note, however, that line 88 carries 150 volts positivedirect current from this power supply.

The series resistors 89 and 85 connected to voltage su'p ply 88 on oneend and through the secondaries of :transformer -77 to ground on theother provideavoltage divid-1 ing .circuit which gives a positivebias'to-the grid of tube 81. The plate voltage of .tube k87 is'obtainedthrough resistor 91 and the cathode ,of that tube is grounded.'

Tube 87 thus takes the pulse from the secondary of transformer 77 andshapes it for actuation of the cycle computer circuit. This pulse havingresulted from vthe discharge of condenser 76 is substantially of asquare wave form and has been further shaped by the limiting action ofthe circuit associated with tube 87.

The output of this tube is coupled to the entire cycle computer circuitthrough isolating diode circuit associated with diode 92 and representedin Fig. 1 by isolation diode circuit 5. This couplingis from the plateof tube 87 through lead 93 and capacitor 94 to the plate of diode 92.The plate of this tube is returned to vground through resistor 95, thus,in conjunction with capacitor 94, differentiating the input to thistube. The cathode of diode 92 is connected through lead 96 to lead 97which in turn is connected ,through lead y98 and resistor 99 to. ground.An indicator light, preferably a neon tube 100 with incorporated seriesresistor -101, is connected bey tween lead 93 and lead V102 andthelatter passes through resistor 103 to ground.

Thus it can be seen` that the positive phase .of the wave output oftriode 8 7 will pass through the circuit of diode92 through leads 96 and9S to the grid of tube 110,` and the diode 92 effectively isolates thepulse forming tube 87 and its preceding circuit from the circuitfollowing diode 92. Whenever there is an output wave fromapulse formingtube 87, Ait will also serve to light neon: indicator light 100 and soinform the operator that that circuit is operated.

It will be noted that the outputs of all fourof the isolation diodes, asrepresented by tube 92, are connected to lead 97 and thus through lead98 to the `grid of triode 110. Likewise, all of the indicating neonlights, such as light 100, `are at the potential of lead 102 `to provideproper operating point for these lights.

Triode 110 and its associated circuits make up the pulse Shaper circuit19 previously referred to. This circuit receives positive pulses fromthe output of the various isolation diodes and has as itsA output asharp nega.- tive pulse which has been further shaped. The plate oftriode 110 is connected to. D.C. voltage line 88 through resistor 111.The cathode. is biased positively by the voltage divider circuitconsisting of resistors 112' and V103 connected between positive line 88and ground. The cathode is also connected to ground through condenser113.

The output of the pulse shaper circuit of tube 110 is led from the plateof that tube through lead 1,17, condenser 118 and lead 119 to both ofthe cathodes of the double triode 120, 121. Double triode 120, 121 ispreferably of the 5965 type and this tube and its associated circuitsmake-up the, ip-op circuit represented by numeral 21 in Fig. 1. A

The ip-tlop circuitvof triodes 120 vand 121 is of a substantiallyconventional nature. The plate of tube -120 is connected to the sourceof positivo D.C. potential throughresistor 122 Vand `lead 123. Theoutput of that plate passes through leadV 124 and the parallel combina-Vtion of resistor 125 andv condenser 126 tothe grid of triode 121. Theplate of triode 121 obtains its positive D.C. .potentialthrough resistor12S. The output of the plate of triode 121 passes through lead 129 tothe parallel combination of resistance 130 and condenser 131 to the gridof triode 1,20. The cathodes of the/two tubes are interconnected throughlead 133 which is grounded through resistor 134,. The grid` of triode121 is grounded through resistor 135. Thegrid of triode 120 passesthrough lead 137, resistor 138 and lead 139 to junction 140 associatedwith 'terminals of switch 141. YSwitch 141; as willbe described below,is lane switch 22 o fV Fig. 1. Junction 1401's directly connected to thepositions of lane. switch-141% representing .2. 3 and. 4 lanes. H1t

`ground through lead 164 and resistance 165.

connected through resistor 142 to the lterminal' represent ing one lane.If, however, it is in the position representing one lane, there will bethe series resistor 142"in:,the circuit, contact arm 180 Aconnecting vialead 188 to ground.

The parameters of the ip-llop circuit are so adjusted that for everypulse applied to its input, lead 119, there will be one-half cycle ofoperation, that is, one-half of the double triode will switch fromconducting to nonconducting and the other half from non-conducting toconducting, as long as resistor 142 is not in the circuit. Under thesecircumstances, therefore, for every two input pulsesapplied to thecathode lead 133, one full cycle of operation will result. However, whenswitch 141 is in the one lane position and resistor 142 is .in :thecircuit, the ip-op circuit will then act as a one-shot, multi-vibratorcircuit and a full cycle willl be etected -by each input pulse.

As can be seen then when the circuit is adjusted for the 2, 3 or 4 lanepositions, the two'pulses resulting from one automobile crossing aparticular detector will result in but .one Cycle. With a singledetector in use, that is with switch 14,1 in the one lane position, twofull cycles will result. This, however, is compensated in the subsequentAone-shot, multi-vibrator circuit 27, previously mentioned.

As with any circuit of the nature of the hip-flop circuit formed bytubes and 121, the output is in the form of a square wave. This outputis preferably taken from the plate of triode 120, through leads 124 Aand144,

condenser 145, lead 147 to the grid of triode 148. Lead.

147 is grounded through resistance 149 thus serving to differentiate thesquare wave output of the flip-hop circuit producing a differentiatedwave consisting of a series of positive pulses, one for each outputcycle of the flip-flop circuit.

Triode 148 and its associated circuits constitute `the pulse shaper 25referred to in Fig. 1. The plate voltage is obtained from line 88through resistor 152. rIhe grid of triode 148 is negatively biased byapplying a positive potential to the cathode of this tube through thevoltage divider circuit made up of a series of resistances 153 and 155which are connected between line 88 and ground, the cathode beingconnected to the midpoint on these resistors. The cathode is connectedto ground also through condenser 156. Thus, this pulse shaper tube 14Sserves to amplify and shape the positive input pulse applied to its gridand produce a negative output pulse of predetermined form and amplitudeon lead 15.8 running from the plate of that tube.

This negative pulse is led through lead 158, condenser 159 and lead 16)to the plate of triode 161. Triode 161 and triode 162 are preferably adouble triode tube of the 5965 type and, together with their associatedcircuits, make up the one shot timed multi-vibrator circuit 27 referredto in Fig. 1. This multi-vibrator circuit is substantially of the normaltype, except that it provides careu'llycalibrated'means for varying theRC constant by the capacitance and timing adjustment by voltage and thusfor varying the period of the square wave out:- put. The plate of triode161 is connected -to the source of D.C. positive potential 88 throughlead 169 and rcsistance 163. The cathode of this tube is connected toThe plate of tube 162 is connected to the D.C. potential 88 through lead168, and resistance 169. The cathode of this tube is grounded throughlead and resistance 165. The plate of triode 162 is connected with thegrid of triode 161 through leads 168, 172 and the parallel combinationmade up of resistor 173 and condenser 174. The grid of triode 161 isalso connected through resistor 175 tol ground.

It is ,in the grid circuit of triode 162 that the aforementionedcalibrations of the output wave as to period arey obtained; This grid isconnected through leads 17.6, and'.

177 to the other half of switch 141. This switch is a gang switch havingtwo four position contacts. One side of the gang has previously` beendescribed in connection with the ip-flop circuit and' junction point.140. The other half of this gang switch serves to provide thecapacitance in the connection between the grid of tube 162 and the plateof tube 161. Thus, lead 177 connects to the contact arrn of the secondhalf of the gang switch 141 and may thus be connected to any one of fourpositions which represent the number of lanes or detectors in use. Theterminals for the one and two lane positions are interconnected as onecircuit, bridged by lead 178, and led through condenser 179 to lead1.82. The contact position for the three-lane connection leads throughcondenser 183 to line 182 and for the four-lane position throughcondenser 184 to line 182. Lead 182 goes through lead 160 to the plateof triode 161. Thus, the capacitance for the RC constant of this half ofthe multi-vibrator circuit may be varied.

Capacitance 179 is preferably 0.01 microfarad. Capacitance 183 ispreferably 0.0068 microfarad and capacitance 184 preferably 0.0051microfarad. The ratio between these three capacitances, as can be seen,is substantially that of the reciprocals of 2, 3 and 4 respectively.Thus, the time constant can be varied in proportion to the number ofdetection units in use. This variation is proportionate to the number ofdetection units and so can serve to adjust the percentage densitydetermination in accordance with the number of lanes used.

As previously described, when there is but one lane used the first halfof gang switch 141 adds resistor 142 to the tiip-op circuit, making it aone shot multi-vibrator and so doubling the number of output pulses fromthe dip-flop circuit per input pulse in comparison to the number hadwhen the resistor 142 is out of the circuit as when gang switch 141 isin either the 2, 3 or 4 line position. This variation compensates forthe lack of aV separate larger condenser in the circuit leading betweenvthe grid of tube 162 and the plate of tube 161 when the switch is set inthe one-lane position. Accordingly, when the unit is set for one-laneoperation, the time period of the output wave of the multi-vibratorcircuit of tubes 161 i the grid of tube 162 is provided by theconnection of grid lead 176 through lead 185 and resistor 186 to thevariable tap of potentiometer 187. This potentiometer impresses apositive D.C. voltage upon the gridof tube 162 through the voltagedivider circuit connected between the D.C. line 88 and ground. Thiscircuit is made up of resistor 190 in series with variable resistor 191,parallel resistors 192 and 193, variable resistor 194 and resistor 195.Resistor 192 is the resistance of potentiometer 187. Variable resistors191 and 194 are calibrating resistors used solely for adjustment of thecircuit.

Potentiometer 187 is the traflic density control for the 100% indicationon the density meter to be described below. Adjusting the potentiometer187 toward the end of higher potential causesthe time to becomeshorter'as would correspond to a high density setting and, conversely,adjusting the potentiometer 187 toward the lower potential and providesa longer time period before tube 162 returns to its normal conductingcondition, corresponding to a low density setting.

As will be described below in more detail, the object of theadjustmentsobtainable in the length'of the period of the youtput of thismulti-vibrator circuit through potentiometer 187, in conjunction withresistor 186 and the condenser half of switch 141 are to vary the periodin accordance with the number of detectors and the predetermined traiicdensity percentages of the highway in question. Accordingly, since theperiod of theoutput wave from the multi-vibrator determines the readingsand of tubes 161 and 162 is preferably taken from the plate ofl tube 161through leads 160, 182, 196, condenser 197, and lead 198 to the grid oftriode 200. Triode 200 and its associated circuit is the chargingcircuit-switch 34 re-' ferred to in Fig. 1. The plate potential for thistube isv obtained from D C. line 88 through lead 201 and resistor 202.The grid of tube 200 is held at a positive potential of Volts but it isconnected to lead 88 through lead 201 and resistance 203. The cathode ofthis tube is grounded.

As will appear below, the timing in this electronic cycle computer isdetermined by passing known amounts of charge through a resistor yforeach actuation impulse received from the multivibrator. In order tosecure uniform charge from each actuation, the timed output of the oneshot multivibrator, as received through leads 160,

182 and 196, is passed via condensed 197 to the grid of' switch tube200. This tube is normally conducting due to the positive grid bias.Upon receipt of a timed negative', impulse from the one shotmultivibrator, tube 200 be comes non-conducting and, therefore, itsplate voltage` rises-to the applied D C. potential of 150 volts. This:positive change in voltage is directly connected via lead 204 through 4microfarad condenser 205 and lead 206i to resistor 207. Essentially nodrop occurs across condenser 20S during the timed interval so that, ineffect, the full change in voltage which occurs in the plate circuit ofswitch 200 is applied to resistor 207.

Resistor 207 is connected to the plate of the diode tube 210. Thecathode of this tube is connected through lead 211 to the parallelcombination of resistor 212 and 2A microfarad condenser 213 and thenceto ground. Thus the change in voltage applied to resistor 207 chargescondenser 213 through diode 210. Resistor 207 controls the current, andthe length of time that the one shot multivibrator is turnedonv(ca1ibrated as above described) determines the amount of chargeapplied to resistor 212 and condenser 213.

Also connected to lead 206 through lead 215 is the cathode or diode 216.The plate of this diode is connected through lead 217 and resistance 218to a source of 150 volts negative D.C. potential is obtained from thepower supply.

This plate is alsorconnected through lead 220 and re-y sistance 221 tolead 215. The charge side of condenser 213 is applied through lead 225to the grid of triode 226. This tube and-its associated circuits arereferred to in Fig. V1 as the instantaneous density measuring circuit39. The cathode of tube 226 leads through resistance 227, lead 228 andresistance 229 to ground. The cathode is also connected through resistor230 to lead 217. This triode 226 is connected as a cathode follower forpurposes to be later described. The plate of tube 226 is connectedthrough lead 233 to the cathode of triode 234, the plate of which isconnected to a source of 300 volts positive potential identified by line235. The grid of this latter tube is also connected to this potentinalthrough resistance 236. This grid is connected to the plate of gasfilled tube 240, the cathode of which is connected through line 241 tothe cathode of triode 226.

Thus it can be seen that the voltage on condenser 213 is applieddirectly to the grid of tube 226. Since this latter tube is a cathodefollower circuit arrangement, the cathode essentially follows the gridvoltage and through a potential divider combination comprising resistors230 and 218, the voltage from the junction of these two resistors passesthrough diode 216 and is used as the restoration voltage for the oneside of condenser 205 when the switchtube 200 is turned off. Therefore,the combination operates such that if a timed detector impulse isreceived, an added potential difference appears at resistor 212 andcondenser 213. Since the side of con' denser' 2.95. f totana-rse 2.0.7isI retntned entita-.end Of: each. @sie to essentiallr the Same voltagethat then exists on condenser 21,3@ asya. result ofthe voltage divider`cireuit; associated;- with. diode 2 16,l the arrangement provides thelcharging. reSSIQl'. 2.07- withthe Seme voltage. for. @acht impulse.:regardless; Qt. the voltage existing on condenser 21,3, This allowsffor#y alinear in-A crease of the voltage on condenser: 213Correspondingto the-numberofg impulses.

Thus, it cangbe seen lthatfthe voltage onv condenser-v 213 is, afunction ofl the number of; impulses. received by: it perjunittimetogethen withl the RQ constant which determines its discharge time-`Resistor 2 12 is preferably L0 megphms. and; Condenser; 2.13,. 2.'.mictofarads.. proerably 10 mecohmsandcndnser 1'3. microtarads, pro.-vidinga timeI constant ofn 2Q seco t This- 20 second; period. is, hereinreferred to. as the-instantaneous;reading,v since the voltage on.condenser; 2,13;- proportionate to thenumber. Qffimrulsssper.unittimeove-rtthe 2.0 seconds; inst'prec,eding- The Alta-srVCorresponding; to.; instant densitymay: beV measured;` atthe;catl'iorlgz;l of-, tube' 2,263.' In order to, intr. more thelimit of;Iiueanityt Ofzthc operation ofi this: ein. .uit, g as tubo2.40ashasrereyiouslyf beendescribed, is

connected. to the cathode. circuit. o f tube11226. with. its..

voltage for, tube` 22,6;as gridgvoltg is .applied toit. If.` thetubesfZfw and:234awerefnctiprnvideditheilargevoltagef. increaseatthetcathodeot: tnbc 22.6 wonld-consumeimosr' 0i they cathode. ton1atetvoltagef-onr-.thisr tube-and, there. fQte,.there-.Would;beiConsiderable.droppingtofor decay;

' Ofcthe linearity Qt: ontput; october- 221iI for latgetiuputvoltages...

. The average;densityW measuring andi-indicatingv circuiti 44 and theup-down averaging time circuit '431er Fig; 1v willI nowbe described.`The cathode voltagefottubez`226 taken from.- line; 241` is; aA` DE..voltage. corresponding. to. the instantaneous trafiicydensity: This;voltage. islnow which is variable from one tonine minutesxin order toobtain, an; average density. measurement xover the selected longen timeperiod, Accordingly, the voltage on line`241 is., led through li n e 242. to. thelowerendof the? group ofl seriesliresistorsgZf, 244, 2.45,.246', 2471 andz248. The junptiond points; 0fthese. resistorsare: each=connected to a terminal of. the..r multifposition; switch- `250, theyoutput fromihs; switch being obtained.on.lne 255; Line-'255 leads intola; second multi-position;v switch. 2561 having termina-1s;associatedwith-.a-.second groupof comparableseries, resistorsy 257258252.260, 261 and 262. Thesey resistors v are connected. .throughlines265,. resistance. 266 andline 267 to seriescondensers 268:?and265l`respectively;

Condenser 269 has,.a dual function.v PlsidcterminedA voltage with..respectn to:` ground sov that whenv the apparatus;.is: firstturned ion-,, the apparatus operates.; as if this; voltage were` storedl in`condenserV 268V and thus the apparatus will'startauptat atpredetermined"desired.startingtlevelzofthe or'dersof 70% -onithe O 100% Adensityscale,4 for example.v Another function ofiicion-I denser;` 2.6.9.is.` to. perrniticondenserr 26810 V,betoperated' at approximately one;half of;thecvoltagefittwould have to .t have ifits; return. were.connected1zdirectly, to` ground. 1

Thus it Gambe.: seentthatzthe .no ternal..receivedA from dit.yinstantaneousdensita.measuringgctenitaon 1e.ad.s.;2 41. andlsgses.tltrnrshtcnesot.tbecrnastcrsfassnetatedrwnn It: providesvv a thegctcut".offswitch 250 and thence through one of that; resistors associated withcircuit 256 through lead; 265@ resistance` 26,6lead 267 and condenser-s268 and. 269.:A A-,chargeis thus added to condenser 268 in this manner.-'Ihe RCatime constant may be different for a situatiotr where; there isrising voltage as against where the'voltaget is: falling. When thevoltage on line 241 is increasing,. current will ow from line 241through line 275, lint:l 276 and the left side of double diode 277throughlinez27f to switch 256. and its associated resistance. When it;is; decreasing, the flow will be from line 241 through line:

l 242 one of the resistances associated with switch 250;.:

line, 25,5line 278the righthand side of diode 277 and". leadi280,toresistor 266 and beyond. Consequently: the

: tirne,.constant of' this circuitmay be diierent. in periods;

ofY rising voltage from that of decreasing voltage depend-.fingupon-thesettings ofY switches 25.0 and. 256.

Voltage/on line.241y is determined by the 20 second or` instantaneous,traic density, whereas thevoltageon; line: 267JS determined bythe.longerl period or average-rtraic density; the integrating period ofwhich is setfbyf'thet switches; 25,0zand; 2.56.. Thus, when theinstantaneous? traffic density isgfhigher than the average trafficdensity; the'intcgrating rate set by switch 256.wil1 be in effect; and.in. thel reverse case the integrating period. set4 by( switch 2,51iis;in effect, which will correspond generallyg. but not necessarily always,with increasing and decrees` inggtraicdensity respectively.

A condenser 279 is connected across lines 276 and 278*` t toeliminateany 60 cycle hum which may 'existin the circuit.y Y

The object of having two separate banks of resistances;. oneassociatedwith each of switches 250 and 2562istrxz provide f or two different timeconstants for the up-down. averagingv time circuit 43. As stated, whichbank is used. depends. upon whether the voltage represented by theraverage density is increasing or decreasing, that is, wheth.

er; the.. instantaneous density is higher or lower thanthc:`

average density; This is desirable since traffic situationsmay-arise inwhich more rapid change from one cycle:A

A circuitltol another cycle circuit is desirable either when.

the trahiev is increasingV or when it is decreasing. Inshort, greaterflexibility is provided.

LAspreviously mentioned, the positive voltage on con'h denser 268k at.line 267 is a function of the trafc density average over the particulartime period selected by switches 250 and 256. This is referred to as theaverage density. This voltage is applied to the grid of triode 28S,which is wired as a cathode follower. This tube and its associatedcircuits is referred to in Fig. l as the average' indicating measuringcircuit 44. The plate of'this'triod'e' 285 is connected through lead 284to the cathode of`tn`- ode'286, the plate of that tube being connectedto lead' 235,v the source of 300 volts positive D.C. potential.' Thegridof tube 286 is also connected through resistor 287to line235. This gridis connected in addition to 'they plate of gas tube 290,*p1eferably theOBZ type; the cathode is connected through leads 291 and 292 to thecathode of triode 285. Cathode of rtriode 285 .is connected.l

through series Aresistors 293. and 294 to ground, thus,

completing the cathode follower circuit. y

The operation of tubes 286 and 290 in association withtube 285,is. toimprove the limit of linearity of thef opera-l tioniofl thiscircuit andcorresponds in operation to tubes 234 and 240 associated with triode226.

It can be seen, therefore, that the voltage obtained on junction point297 between resistors 293 and 294y fol, lows the voltage applied to thegrid of tubeA 285 and so is .directly proportional to the voltage oncondenser 268 which represents the averagetraic density. Correspondf=ingly, the voltage at junction point 298, located between; resistors 227and229, is proportional to the instantaneous: traffic, density, as: has.been=above described..

Thesefvoltages. amused. to. operate` a.. meter .on a rca aasaoos corderand the cycle'controlling circuits for the distribution network. e

' Two-gang multiple position switch 300 serves to complete the circuitsfor utilization of either of the two voltages. The first gang of theswitch, as represented by the upper half above the insulator 299 in Fig.3, serves to connect either of these voltages or testing voltages withthe milliameter 301 through line 302. vIn the lirst position of theswitch, the instant density voltage from junction point 298 is connectedto the meter through lead 303, variable Calibrating resistance 304, andlead 305. The second gang of the switch 300, when it is in the iirstposition, serves to complete the meter circuit. The other side of themeter is connected through lead 307, resistor 308, lead 309 (whichbridges connecting terminals 310 and 311 when a recorder is not in use),lead 312, the second gang of switch 300, lead 313, and potentiometercircuit 314 connected at the variable tap 315. This po tentiometercircuit consists of series resistors 316, 317, and 318 connected betweena source of 150 volts positive potential and ground. The variable tap315 is on potentiometer 319 which is wired in parallel with resistor317.

When switch 300 is in its second position, the meter and recorder willbe actuated not by the instantaneous density voltage but by the averagedensity voltage. This is obtained from junction point 297 through lead322, variable calibrating resistance 323, and lead 324, connecting withthe second terminal of the first gang of switch 300. The circuit to themeter is then completed, as with the iirst position ofthe switch, exceptthat lead 312 now connects through they second gang of the switch,thence to lead 326 and the variable tap on resistor 317, previouslydescribed. f

The remaining positions of switch'300 are for purposes of testing theaccuracy of the power` supply voltages. When the switch is in the thirdposition, lead 302 going into the meter will then be connected to asource of 300 volts positive potential through resistor 328 and lead329, going into the third position terminal of the iirst gang of theswitch. Lead 312 will be connected through thesecond gang of the switchto ground by lead 334, thus resulting in an application of 300 voltspotential to meter 301.

A second test point is the 150 volt positive potential test obtained inthe fourth positionof gang switch 300 through resistor 332 and lead 333.In this instance, lead 312 from the meter is connected to groundthroughthe fourth position of the second gang of switch 300 and lead330. e v

The negative potential of 150 volts is tested when switch 300is in itsfifth and last position. In that instance, lead 302 is grounded throughthe iirst gang of the switch and-lead 335. The negative potential isapplied to the meter`through resistor 337, lead 338 and the iifthposition `of the second gang of switch 300 connecting to lead 312.` `Itwill be understood that in'each instance of voltage tests, the meterwill have been previously calibrated. Y As previously mentioned, arecorder vof any standard type may be placed in the circuit. v In thisinstance bridge 309 is broken between terminals 310 and 311, and therecorder is connected to these terminals. A bridge is then placedbetween terminal 310 and terminal 339, shorting out resistance 308 andthus maintaining the balance of the circuit.

,One of the primary `objects of the present invention is to provide ameans for switching on one of a plurality of traliic control circuits asselected by the traffic density in the various highway lanes beingdetected. This is best accomplished by the network distribution circuitnow to be described. Y f

Lead 292 connected to the cathode of tube 285 in a cathode follower typeof circuit reflects, as had previously" been described, a voltageproportionate to the positive circuits for theremaining tubes arecomparable.

voltage on lead 267. This voltage is a function of the' average trafficdensity over the time period set in aecordance with switches 250 and256. Thus, the voltage on lead 292 is a positive direct current voltagefollowing slowly over the averaging period in accordance with mally inthe down position as shown in the drawings when their respective relaycoils are de-energized. Thus, relay coil 352 actuates armatures 357 and358; coil 353 ,actuates armatures 359 and 360; coil 354 actuatesarmatures 361 and 362; coil 355 actuates armatures 363 and 364; and coil356 actuates armatures 365 and 366.

The grid of triode 346 is connected through lead 370 to armature 357 andfrom there through condenser 371 to ground. The cathode of 4that tube isgrounded. The The grid on tube 347 is connected through lead 372 toarmature 359 and then through condenser 373. The grid of tube 348 isconnected to armature 361 by lead 374 and then through condenser 375 toground. The grid on tube 349 is connected to armature 363 through lead376 and then through condenser 377 to ground. The grid of vtube 350 isconnected through lead 378 to armature 365 and then through condenser379 to ground. The cathodes of each of these tubes are grounded.

Each of these five triodes has a grid signal applied to it which isafunction of the voltage on line 345, the voltage set on a Calibratingvoltage dividing network, and whether or not the tube is at a given timeconducting or non-conducting. The voltage dividing net-work is `made upfirst of series resistors 385, 386, 387, 388, 389, 390, 391, 392, 393,394, 395, 396 and 397 connected between a source of minus 150 volts D C.potential and ground, the first of these resistors being a grounded one.Resistors 385 and 397 are variable resistors so that the initialadjustments to the circuit to provide for zero percentage and traliicdensity may be made.

The Vvoltage ldividing net-work for'tube 346 is made vup of lead 400connected between resistors 386 and 387 and going to parallel resistors401 and 402 which are connected to lead 403 which runs to the junctionpoint between resistances 391 and 392. Resistors 405 and 406 are seriesconnected between input lead- 345 and a variable tap on yresistance 401.The lower contact point 407 for armature 357 is connected betweenresistances 405 and 406. Resistances 409 and 410 are connected in seriesbetween lead 345 and the variable tap on resistance 402. The mid-pointof these two resistances is connected to the upper contact point 411 onarmature 357.

The circuit arrangement for obtaining grid bias on the other four tubesis comparable, thus parallel resistances 415 and 416 are connectedbetween the junction point of resistances 387 and 388 and thejunctionpoint of resistances 392 and 393. Series resistors 417 and 418lead from line 345 to the variable tap on resistance 415, theirmid-point being connected to lower contact point 419 and armature 359.Resistances 420 and 421 are connected in series between line 345 and thevariable tap on resistance 416, their mid-point being connected to theupper contact point 422 of armature 359.

Parallel resistances 425 and 426 are connectedv between the mid-point ofresistances 388 and 389 and the midpoint of resistances 393 and 394.Resistances 427 and 428 are connected in series between line 345 and thevariable tap on resistance 425, their mid-point being Aconnected to thelower contact point 429 of armature the lower contact point 449 ofarmature 365.

361. Series resistances :430 .and 431 are connected in `series betweenline 345 and the variable tap on resistance 4.26. Vtheir midpoint .beineConnected Vt0 the upper Qontact point 432 of armature 36,1. Parallelresistances 435; `and 436 are connected between the junction .ofresistances 389 and 390 and the junction to resistances 39.4 and 395.Series resistors 437 and 438 are connected between lline 3.45 and thevariable tap on resistance 435, their midpoint being connected to thelower contact point 439 .of :armature 363. Series resistors 440 and 441are connected between line 345 and the variable tap on resistance 436,their mid-point being connected to the Icontact point .4.42 of armature363.

Parallel resistances 445 and .446 are ,connected between the junction ofresistances 390 and 391 vand the junction of yresistances 395 and 396.Series resistances 447 and 448 are connected between line 345 and thevariable tap and resistance 445, their mid-point being connected toV,Series ...resistances 450 and 451er@ @arrested between line 34.5 andthe variable tap on resistor 446, r4and Vtheir mid-point is Connected t0the upper vente@ .arm 4529f1rmature 36,5-

Associated with ,each .one .o f .the tive triodes and their respectiverelays are ve distribution circuits .which are designed to provide avoltage on .any one at any given time to actuate the outside circuits.The objective is to `have but one outside circuit, such as .a tratiiccontrol circuit, operated at any given time and to switch lfrom any oneto any other of the actuating circuits in .accordance `.with the controlvoltage found on line 345 and representting the average traiilc density.

A voltage to be applied to the trahie .control .ein Auit is representedat 460 as positive voltage. As shown in the drawing, this voltage goesthrough lead 461 through `arrna- Ature 366, lower contact point 462,lead 463, armature 4364, 4lower contact point 465, lead 466, armature362, ylower .contact point `467, lead 468, armature A360, lower .contactpoint V469, lead .470, armature V358, vlower .contact point 471 and lead472 to output control point A. `It will be understood that this circuitwill be lbroken Vif any o f the ve armatures are raised `as would occurwhen `the respective armature coil is energized. This latter occursvwhen the particular tube in series with the coil :becomes conducting,as will be described below. Associated .with armatures 358, 360, 362,364 and 366 are upper contact lpoints 475, 476, 477, 478, 479,respectively, which conl-nect the armature to output control points B, C,D, E :and F, respectively. The six control points A through F arecomparable to the similar control points shown in the above mentionedPatent Number 2,288,601. It Vis therefore seen that there have beenprovided six different control possibilities in this circuit, though thecircuit may easily be designed for a greater or fewer number, if such isdesirable.

So that the operator of the unit may know which par- ;ticular outputcontrol circuit is in operation at a given time, there are provided neonindicating lamps 480, 481, .48.2, 483, 434 and 485 connected between therespective lcontact points A through F ,inclusive and ground. Asindicated in the circuit, each of these neon lights whas incorporatedwithinits owncircuit a series resistor; as va. satisfactory tube forthis purpose would .he one of the NESl type.

As previously mentioned, this distribution netework control circuit iscontrolled by the positive voltage on line 345. In the drawing as shown,all of the .coils 352 through 356 are de-energized and their respectivearmatures are in their normal or resiliently biased position so that thecontrol voltage from point 4,60 is fed to con- Atrol point A. This wouldindicate that the voltage on line 345 is very low due to lowtraicdensity, for example.

The points in terms .of percentage traliic density lat which it isdesired that the distribution net-work Ibe Wi-.lished from onecontrat-reim 10 @ether when the 1,6 voltage `ori-line 3,45 isincreasingAare se t by adjusting the variable taps on resistances 401', 415, 425,435 and respectively. Since each of these variable taps is associatedwith a voltage divider circnit, the voltage obtained on each of thesetaps can be varied. These voltages, however, should be so adjusted as tobecome more negative as we move from the tap on resistance 401 to thetap on resistance 445. This adjustment then, as will be later described,sets the point at which the respective tubes become conducting and soenergize their respective relay circuits.

Comparably, the taps on resistances 402, 416, ,426, 436 and 446 areadjusted for use when the voltage on line 345 is decreasing. Thesevoltages also are more nega; 'tive with respect `to each other as we gofrom that on the ,tap associated with resistance 402 to that on they'tap associated with resistance 446. It is to be noted, however, thatthe voltage ,on the tap associated with resistance' 401 is less negativethan the voltage on the tap associated with resistance 402. This alsoapplies to resistances 415 and 416, resistances 425 and 4 26,resistances 435 and 436 and resistances 445 and 446. This difference inyoltage allows the trafic density percentage, at which point the circuitswitches from one output control to another, ,to be greaterforincreasing as against decreasing traflc volume.

As stated above, the relays as shown in this drawing are all in theirde-energized positions. In this situation, the grid voltage on triode346 is obtained through lead 370, armature 357, and lower contact point407; it will be seen that series lresistances 405 and 406 comprise avoltage dividing net-work as between line 345 and the tap on resistance401, thus providing the grid voltage on lower contact point 407. Whenthe voltage in line'345 Vbecomes sufciently high to bring the voltage.at point 407 above the cutoff voltage for tube 346, this tube will thenconduct. Once it conducts, coil 352 will be energized and relayarmatures 357 and 358 will beshifted to their energized positions,contacting the `upper c ontact points 411 and 475, respectively. TheCcontact arms 358, 360, 36,2, 364 and 366 Vare all adjusted to makebefore they b reak contact.

The contact arms 357 and 358 having connected to their respectiveenergized contact points 411 and 475, it will be seen then that thevoltage 460 will no longer be applied to control point A but will now beapplied to control point B, and that the grid voltage for tube V346 willno longer be obtained from point 407 .but will be obtained from point411 (point 411 being connected to the mid-point of resistors 409 and 410which make upna voltage dividing network between line 345 andpotentiometer 402), and the voltage on the grid of 4tube 346 willthereafter be controlled in accordance with the voltage set on the tapon resistance 402 for decreasing vtratiit: density. Since the voltage onthe tap on resistance 402 is less negative than the voltage on the ytapon resistance 401, the grid voltage resulting iwill be vabove thecut-off point until the voltage on line 345 drops .below that which theline had when tube 346 rst became conducting.

It will be seen due to the different and more negative settings of the.potentiometer networksassociated 4with Vthe other four tubes that atthe .point at which the voltage on line 345 'becomes Vsuliicientlypositive to cause tube 346 to conduct, as previously described, it rwillnot be suddciently positiveiito cause any yof the .remaining tubes toconduct. As it increases, however, the voltage on lower contact point419 likewiseincreases in-accofrdanee with the setting of vthe variabletap associated with variable resistance 415. At a `certain point, vasthe voltage in line 345 increases, the voltageoncontact point L419,willreach the cut-ott voltage of tube 347. l Since this voltage ,atpoint 419 is applied to the grid of tube 347 throughcontact arm 359 and.lead 372, this tube will then become conducting. When ythis occurs,.relay coil 353 .will ,be energizedgnd relay amis .359 and 360 movetotheir 117 second position, justas happened with respect to the circuitof tube 346. Since contact arm 360 is no longer contacting lower point469, voltage 460 will no longer be applied to control point B, butrather it will be applied through upper contact point 476 to controlpoint C. This is so even though tube 346 is conducting at the same timeas tube 347. v l

lf the voltage on line 345 continues to increase, tubes 34S, 349 and 350will alsobecome conducting in thatY order and will thus actuate therelays in the same manner as in prior stages and shift the controlpoints. 1t will be noted in this respect that the control point which isenergized by the potential from point 460 will be the one associatedwith the most righthand of the live triodes as shown in the drawing.

Assuming that the voltage on line 345 is high enough for tubes 346 and347 to be made conducting but not high enough for the remaining tubes:to be made conducting, then it will be control point C that will beenergized in accordance with ythe previous description.

lf the voltage Yon lline 345 now decreases there will come a point atwhich the voltage on upper contact point 422, as obtained from thevoltage dividing network made up of resistances 420 and 421, will dropbelow the cut-oit` voltage for triode 347. The term cut-off here meansthe point at which suicient plate current owsvto operate relay 353, thisbeing preferably near the maximum slope on the 1/Eg characteristiccurve, rather than at the actual point of cut off of plate current 'bygrid bias'. At this instant relay 353 will become de-energized and relayarms 359 and 360 will drop to their de-energized normal positions. Thiswill disconnect control point C and connect control point B (since tube346 will at that point be conducting). It will also provide that thebias on the grid of tube 347 will now come from point 419 asr previously described.

As the voltage on lineV 345 continues to decrease, then grid voltage onpoint 411 which is being applied to tube 346 will finally go belowcut-oi and that tube will also become nonfconducting, shifting thecontrol point from B to A in a comparable manner.

Thus it can be seen that the tive triodes, 346, 347, 340, 349 and 350and their associated relay networks provide a means by which theparticular control point energized at a given time may beinstantaneously changed to any other control point as determined solelyby the average traflic density control voltage impressed on line 345. Itwill also be seen that, if desirable, the particular traffic controlvoltage at which the shift is made from one control point to anothercontrol point may be diierent, depending upon whether the voltage inline 345 is decreasing or increasing. s

In the practice of thisy invention, it is preferable to have thevariable taps associated with resistances 401, 415, 425, 435 and 445calibrated in terms ot the percentage traffic density at which itisdesired to have the control points switched during periods of increasingtrafc density. Comparably, it is desirable to have the taps on theresistances 402, 416, 426, 436 and 446 calibrated in terms of percentagetraic density for periods in which traic is decreasing.

Turning to Figure 6, we have there illustrated a control board 489 oftype which could be used within the described electronic cycle computer.In the operation of the unit, the calculated 100% tratiic density of theparticular highway being detected is set with knob 490 which actuatespotentiometer 187. The number of lines being detected, that is, thenumber of detectors being used, is set with knob 491 Ywhich operateslane switch 141. The desired averaging period for increased density isset with knob 492 which actuates multiple position switch 256. Likewise,the desired averaging period for decreasing density is set with knob 493which is the same as multiple switch 250. The detectors that are inoperation may be controlled by the onfoi switches identied as 494, 495,

respectively.

18 496, and' 497 which are the switches located on the incoming lines70, 71, 72 and '73 from the detectors. Each detector switch has locatedabove it on the panel an indicator light, such as neon light previouslydescribed.

The point at which the distribution network control circuit is to switchfrom one control point to another for increasing tratlic is set 'byknobs 500', 501, 502, 503 and 504. These knobs control the taps onresistances 401, 415, 425, 435 and 445 respectively. The point of switchduring periods of -decreasing traiiic density is set by knobs 505, 506,507, 50S and 509 which` control the taps on variable resistances 402,416, 426, 436 and 446, these latter knobs being concentric with theknobs 500 to 504, It has been found that it is preferable to set thepoint for decreasing density switching approximateiy 5% below that forthe increasing density switching. Thus, for example, knob 505 might beset for a 20% trafic density while knob 500 would be set for 25% trafficdensity.

These concentric knobs are interlocked by means of the peg 520projecting below the inner knob and the pin 521 shown to the left ofthis peg and mountedon the outer knob, so that the inner knob cannot beset any higher than 5% below the outer knob on the scale.

Associated with each of the concentric pairs of traffic control densityknobs (as knobs 500 and 505) is an indicator light to show which controlcircuit is in operation at a particular time. Thus, on the panel arelights-510, 511, 512, 513, 514, 515 which correspond to neon lights 430,481, 482, 483, 484 and 485 respectively.

Also mounted in the panel board of Figure 6 is a percentage traflicdensity meter 516. This is the meter 301 shown on the circuit diagrams.Located below the percentage traffic meter 516 is a meter selectorswitch 517. This is switch 300 of the circuit and shows points forshowing instant density, average density and checking the voltage aspreviously described. Preferably contact points 310 and 311 for theconnectionof an outside graphic recorder, such as a recordingmilli-amrneter properly calibrated, will not be on the panel board butthis, of course, is optional with the user.

The operation of the electronic cycle computer of this invention hasbeen described above with reference to the particular stages of thecircuit under consideration and its operation has been also explained inthe description of the panel board shown in Fig. 6.

Once the detectors have been properly connected in accordance with theusual practice and the control points A through F have been alsoconnected to the usual types of selective traffic actuating mechanisms,the operator then sets the controls on the panel board of Fig. 6 for thespecific mode of operation desired. After checking the voltage by usingthe third, fourth and fifth positions of the meter selector 517 andnoting the voltages on meter 516, the calculatedk trafc density for thehighway under consideration is set on density control knob 490. In Fig.6 this knob is shown as set for a highway havinga calculated 100%traffic density of 700 vehicles per hour per lane.

The vehicle detectors are turned on, as desired, with knobs 494, 495,496 and 497 and the number of detected lanes set with knob 491. Theoperator then determines the desiredaveraging periods for increasing anddecreasing densities, in accordance with the trac conditions eX- pectedto be encountered, and these are then set with knobs 4972 and 493.

The switchover points to shift the operation from one cycle, that is onecontrol point, to another are then set, both by means of dials 500 to509, inclusive, as previously described. The setting of these dials willdetermine invterms of percentage of traffic density when the switch willbe made during increasing and decreasing trac periods. An example ofpossible settings for the traflic density switch controls 500 to 509 isillustrated in Fig. 7. This chart shows the switchover points for thevarious cycles as the panel board has been set in Fig. 6. Thus,beginning with a zero percentage traffic density and increasing to 100%it will be seen that cycle A will be controlling until the traic reaches25% density, at which point cycle B will control; when 40% is reached,it 4will switch to cycle C where it will remain until it reaches 55%, atwhich point a switch is made to cycle D. At the 70% point, a switch willbe made to E and at the 85% point'to F. When the percentages aredecreasing from 100%, it will be seen that the circuit will switch tocycle E at 80%, to cycle D at 65%, to cycle C at 50%, to cycle B at 35%and to cycle A at 20%. It should be noted that due to the design of thedistribution network control circuit, these switches from one to anothercycle will be made substantially instantly as the voltage in line 345corresponding to changes in trafc density varies.

e As previously described, the actuation of any of the detectors by apassing vehicle serves to close the detector circuit twice (once foreach axle) thus producing a pulse wave in the primary and secondary oftransformer 77. This wave will be formed in tube 87 and the positivephase of this wave will pass through isolation diode 92 to leads 97 and98 to pulse sharpening tube 110. At the same time, these input pulsescan be observed visu- -ally on neon tube 100 on the panel board. Theoutput of pulse sharpening tube 110 will be a sharp negative pulse whichis carried by lead 117, condenser 118 and lead 119 to the ip-op circuitrepresented by triodes 120 and 121. Except when the circuit is set forsingle 'lane detection, each pulse will cause one-half cycle ofoperation of the ip-flop circuit, thus producing one full cycle forevery vehicle detected. Where single lane operation is called for, twocomplete output cycles will result from each vehicle.

` The square wave output of the Hip-flop circuit is carried out by lead124, the differentiating circuit made up of condenser 145, lead 146 andresistance 149, and lead 147 to the grid of a second pulse sharpeningtube 148. Since the wave is differentiated it will take a pulse form andthe output of the pulse sharpening tube 148 will be a series of negativepulses impressed upon lead 158.

This signal then passes into the biased multi-vibrator circuitrepresented by triodes 161 and 162. The period of this circuit has beenpreviously adjusted by the psitioning of switch 141 and potentiometer187 and, as a result, the output of the multi-vibrator circuit is a`wave of predetermined amplitude and carefully calibrated period. Thisoutput wave is fed into the grid of charging circuit switch tube 200 andserves to change it from normally conducting to temporarilynon-conducting, in accordance with the predetermined period ot themulti- Ivibrator.

The output from the tube 200 passes through condenser 205, resistance207, and diode 210 vto the parallel combination of resistance 212 andcondenser 213. The magnitude of the charge applied to condenser 213 willbe determined by the period of the multi-vibrator circuit andconsequently the voltage across the condenser 213 at any particular timewill be a function of the number of charges the condenser has receivedand the magnitude of those charges for a given value of resistor 212.Thus, this voltage represents the traffic density calibrated in terms ofpercentage on the basis of the calculated 100% traic density for thehighway (switch 490).

vThe voltage on condenser 213 is led through lead 225 "to theinstantaneous density measuring and indicating circuit as represented bytube 226 and its associated circuits. The output voltage of 226 isobtained on lead 241 and passes through the average density measuringand indicating circuit to condenser 268 in the marmer previouslydescribed. The voltage on condenser 268 vwill 20 represent the averagetraic density over the previously selected time period.

This voltage on condenser 268 is amplied in cathode follower circuit 285and its associated circuit and passes-first through resistor 293,junction 297, lead 322 and the resistance 323 and lead 324 to switch 300from where it may be used to actuate the meter or recorder. This voltagesecondly passes into lead 292 and lead 345 and is utilized to operatethe distribution net-work control circuit, as previously described.

Although the values employed for resistors and condensers used in thesystem as well as the several vacuum tubes that are employed may bevaried within wide limits according to the network of a particularinstallation the several components described above have been found toproduce good results in a practicable embodiment of the invention whenthefollowing values were employed:

Tubes Ref. No. Tube type Ret. No Tube type 87 5965/,2 210 ALS 92 6AM/2gig "5s14A/2 11%) $6122 zss 5s14A/2 Resistors Ref. No Ohms Ref. No. Ohms81 2K 218 200K 82 17K 221 200K 83 300 227 23.5K 85 100K 229 680 86 100K230 15K 89 3.9 meg. 236 360K 91 20K 243 1s meg. 95 200K 244 6 meg 99100K 245 6 meg 103 20K 246 6 meg 111 51K 247 6 meg 112 200K 248 6 meg122 15K 257 6 meg 125 390K 258 6 meg 128 15K 259 6 meg. 130 390K 260 6meg. 134 6.8K 261 6 meg. 135 100K 262 18 meg. 138 100K 266 6 meg. 142510K 271 100K 149 100K 272 100K 152 10K 287 360 153 20K 293 235K 155200K 294 680 163 15K 304 2K 165 6.8K 308 2K 169 15K 316 75K 173 390K 317400 175 100K 318 100 186 510K 319 400 190 34K 323 2K 191 10K 328 450K192 100K 332 225K 193 50K 337 225K 194 10K 385 2K 195 13K 386 1.8K 20213.5K 387 1.5K 203 1 meg. 388 1.8K 207 27K, 389 2.3K 212 10. meg. 3902.8K

Although the foregoing description has defined the basic concept of theinvention as applied to a vehicular traffic system, it is apparent thatthe invention is not limited to this purpose but is capable of muchbroader application. For example, the device may be used in connectionwith supplying air to a vehicular tunnel for the purpose of ventilation.Obviously, in such an application it is easier to keep the air supplywithin readily predetermined limits in order to provide sufficientventilation for the number of cars using the tunnel and at the same timeto avoid oversupplying the tunnel with a consequent Waste of power. Insuch an application, vehicle detecting devices as described above or ofany other suitable type such as photo-electric, may be placed at theapproaches to the tunnel and the Ventilating machinery may be controlledin very much the same manner as described above to insure adequateventilation as a function of the number of cars using the tunnel. Theinvention is equally applicable in the field of auto mation wherein aplurality of conveyor lines, each carrying a separate component of aproduct, in essence converge at one assembly point. In such anapplication an over-supply or under-supply of any component of theproduct can cause costly and time consuming delays unless detected inadequate time. To those skilled in the control of such processes, themanner of application of the present invention will be readily apparent.

It will be appreciated that the term traffic density is used herein inthe sense of traflic volume per lane or rate of trafiic liow in vehiclesper unit time passing a givenV point or points, depending on whether oneor .more detectors are used. Such trahie volume may be expressed invehicles per hour, per lane for example on adjusting switch @fr The termdensity is also used in its more general sense as the incoming pulserate per unitv time from the input or detector circuits.

It will be obvious to those skilled in the art that the Vv22 severaltriodes 346 through 350 might be replaced by gas discharge tubees of thetype 885 or Thyratron type with an alternating current voltage sourceapplied to line 351 instead of the direct current voltage source 145Bshown, if desired.

From the foregoing description, it is apparent that the several objectsof the invention are achieved. Obviously, many variations may be madewithout departing from the scope of invention and Would includemodifications of both Wave shape and Wave polarity in various of thestages of the circuit.

I claim:

1. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform wave form in response to randomexternal actuation, a timing circuit for the generation of output wavesof uniform shape and amplitude in response to said pulses, an averagingcircuit having a specified time constant for receiving the output ofsaid timing circuit and for generating a voltage functionally related tothe period of and rate of receipt of said output waves, a second avveraging circuit having a specified time constant greater than the timeconstant of'said first averaging circuit for receiving the voltagegenerated by said first averaging circuit and generating a controlvoltage functionally related to the integral of said first voltage overa selected time period, a plurality of utilization device actuatingcircuits, and a control circuit capable of selectively actuating`one ofsaid utilization circuits in accordance with the magnitude of saidcontrol voltage.

2. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform wave form in response to randomexternal actuation, a timing circuit for the generation of output wavesof uniform shape and amplitude and of adjustable period in response tosaid pulses, an averaging circuit having a specified time constant forreceiving the output of said timing circuit and for generating a voltagefunctionally related to the period of and rate of receipt of said outputwaves, a second averaging circuit having a specified time constantgreater than the time constant of said first averaging circuit forreceiving the voltage generated by said first averaging circuit andgenerating a control voltage functionally related to the integral ofsaid first voltage over a selected time period, a plurality ofutilization device actuating circuits, and a control circuit capable ofselectively actuating one of said utilization circuits in accordancewith the magnitude of said control voltage.

3. A circuit of the character described, including a pulse generatingcircuit capable of producing pulses of uniform wave form in response torandom external actuation, a timing circuit for the generation of outputWaves of uniform shape and amplitude in response to said pulses, anaveraging circuit having a specified time constant for receiving theoutput of said timing circuit and for generating a voltage functionallyrelated to the period of and rate of receipt of said output waves, asecond averaging circuit having a specified time constant greater thanthe time constant of said first averaging circuit for receiving thevoltage generated by saidk first averaging circuit and for generating acontrol voltage functionally related to the integral of said firstvoltage over a selected time period, a plurality of utilization deviceactuating circuits, a control circuit capable of selectively actuatingone of said utilization circuits in accordance with the magnitude ofsaid control voltage, and means for indicating the output voltages ofthe respective averaging circuits.

4. A circuit of the character described including a pulse generatingcircuit capable of producing pulses of uniform wave form in response torandom external actuation, a timing circuit for the generation of outputWaves of uniform shape and amplitude in response to said pulses, anaveraging circuit having an adjustable time constant for receiving theoutput of said timing circuit and for generating a control voltagefunctionally related to the period and rate of receipt of said outputwaves, said averaging circuit including means controlled by thefrequency of said output waves for varying said time constant indifferent respects for increasing and decreasing frequency, amultiplicity of utilization device actuating circuits representative ofdifferent segments of a scale of magnitudes of said control voltage, anda control circuit for selectively actuating one of said utilizationdevices in accordance with the magnitude of said control voltage.

5. A circuit of the character described including a pulse generatingcircuit capable of producing pulses of uniform wave form in response torandom external actuation, a timing circuit for the generation of outputwaves of uniform shape and amplitude in response to said pulses, a firstaveraging circuit having a fixed time constant for receiving the outputof said timing circuit and for generating a voltage functionally relatedto the period of and rate of receipt of said output waves, a secondaveraging circuit having a variable time constant greater than the timeconstant of said first averaging circuit for receiving the voltagegenerated by said first averaging circuit and for generating a controlvoltage functionally related to the integral of said first voltage overa selected time period, said second averaging circuit including meanscontrolled by the frequency of said output waves for varying saidvariable time constant, a plurality of utilization device actuatingcircuits, and a control circuit for selectively actuating one of saidutilization circuits in accordance with the magnitude of said controlvoltage.

6. A circuit of the character described including a pulse generatingcircuit capable of producing pulses of uniform wave form in response torandom external actuation, a timing circuit for the generation of outputwaves of uniform shape and amplitude in response to said pulses, a firstaveraging circuit having a fixed time constant for receiving the outputof said timing circuit and for generating a voltage functionally relatedto the period of and rate of receipt of said output waves, a secondaveraging circuit having a variable time constant greater than the timeconstant of said first averaging circuit for receiving the voltagegenerated by said first averaging circuit and for generating a controlvoltage functionally related to the integral of said first voltage overa selected time period, said second averaging circuit including meanscontrolled by the frequency of said output waves for varying saidvariable time constant, said time constant varying means including twoparallel resistance and diode combinations, said diodes being connectedin opposite polarity relationship, whereby said resistance diodecircuits are utilized alternatively in said second averaging circuitdepending upon the direction of the rate of change of said outputvoltage of said first averaging circuit, a plurality of utilizationdevice actuating circuits, and a control circuit for selectivelyactuating one of said utilization circuits in accordance with themagnitude of said control voltage.

7. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform wave form in response to randomexternal actuation, a timing circuit for the generation of output wavesof uniform shape and amplitude and of adjustable period in response tosaid pulses, an averaging circuit for receiving the output of saidtiming circuit and for generating a control voltage functionally relatedto the period of and rate of receipt of said output waves, a pluralityof utilization device actuating circuits, and a control circuit capableof selectively actuating one of said utilization circuits in accordancewith the magnitude of said control voltage, said control circuitincluding at least one twoposition relay having a relay coil, anadjustable source ofdirect current potential, a voltage divider circuitcon- .'24 nected between said applied voltage and said source, and avacuum tube with its plate circuit connected in series with said coiland being biased by the potential from said voltage divider circuit,whereby the conductance of said tube and thereby the energization ofsaid relay coil is determined by said applied voltage.

8. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform wave form in response to randomexternal actuation, a timing circuit for the generation of output wavesof uniform shape and amplitude and of adjustable period in response tosaid pulses, an averaging circuitA for receiving the output of saidtiming circuit and for generating a control voltage functionally relatedto the period of and rate of receipt of said output waves, a pluralityof utilization device actuating circuits, and a control circuit capableof selectively actuating one of said utilization circuits in accordancewith the magnitude of said control voltage, said control circuitincluding at least'one two-position relay having a relay coil, a firstadjustable source of direct current potential, a first voltage dividercircuit connected between said applied voltage and said first source, asecond adjustable source of direct current potential less negative thansaid first source, a second voltage divider circuit connected betweensaid applied voltage and said second source, and a vacuum tube with itsplate circuit connected in series with said coil and being biased by thepotential from said first voltage divider circuit when said tube isnon-conducting and being biased by the potential from said secondvoltage divider circuit when said tube is conducting, whereby theconductance of said tube and thereby the energization of said relay coilis determined by said applied voltage, said biasing being controlled bysaid relay.

9. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform wave form in response to randomexternal actuation, a timing circuit for the generation of output wavesof uniform shape and amplitude in response to said pulses, an averagingcircuit having a fixed time constant for receiving the output of saidtiming circuit and for generating a voltage funcionally related to theperiod of and rate of receipt of said output waves, a second averagingcircuit having a variable time constant greater than the time constantof said first averaging circuit for receiving the voltage generated bysaid first averaging circuit and generating a control voltagefunctionally related to the integral of said first voltage over aselected time period, a plurality of utilization device actuatingcircuits, and a control circuit capable of selectively actuating one ofsaid utilization circuits in accordance with the magnitude of saidcontrol voltage, said control circuit including at least one twopositionrelay having a relay coil, an adjustable source of direct currentpotential, a voltage divider circuit connected between said appliedvoltage and said source, and a vacuum tube with its plate circuitconnected in series with said coil and being biased by the potentialfrom said voltage divider circuit whereby the conductance of said tubeand thereby the energization of said relay coil is determined by saidapplied voltage.

10. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform wave form in response to randomexternal actuation, a timing circuit for the generation of output wavesof uniform shape and amplitude in response to said pulses, an averagingcircuit having a specified time constant for receiving the output ofsaid timing circuit and for generating a voltage functionally related tothe period of and rate of receipt of said output waves, a secondaveraging circuit having a specified time constant greater than the timeconstant of said first averaging circuit for receiving the voltagegenerated by said first averaging circuit and generating a controlvoltage functionally related to the integral of said first voltage overa selected time period, a plurality of utilization device actuatingcircuits, and a Acontrol circuit capable of selectively actuating one'of said utilization circuits in accordance with the magnitude of saidcontrol voltage, said control circuit including at least onetwo-position relay having a relay coil, an adjustable source of directcurrent potential, a voltage divider circuit connected between saidapplied voltage and said source, a second adjustable source of directcurrent potential less negative than first source, a second voltagedivider-'circuit connected between said applied voltage and said secondsource, and a vacuum tube with its plate circuit connected in serieswith said coil and being biased by the potential from said first voltagedividing circuit when said tube is non-conducting and being biased bythe potential from said sceond voltage divider circuit when said tube isconducting, whereby the conductance of said tube and thereby theenergization of said relay coil is determined by said applied voltage,said biasing being controlled by said relay.

ll. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform wave form in response to randomexternal actuation, a vacuum tubejmultivibrator timing circuit for thegeneration of output waves of uniform shape and amplitude in response tosaid pulses, said multivibrator circuit including adjustable gridbiasing means for varying the period of said output waves to compensatefor known differences in the source of said external actuations, an

averaging circuit having a specified time constant for receiving theoutput of said timing circuit and for generating a control voltagefunctionally relatedl to the period of and rate of receipt of saidoutput Waves, a multiplicity of utilization device actuating circuitsrepresentative of different segments of a scale of magnitudes of saidcontrol voltage, and a control circuit for selectively actuating one ofsaid utilization circuits in accordance with the magnitude of saidcontrol voltage.

12. A circuit for selectively connecting one of a plurality of trafiiccontrol `circuits in response to the traffic density as detected on oneor more highway lanes, said circuit including a pulse generating circuitfor producing pulses of uniform wave form in response to externalactuation received from said detecting means, a vacuum tubemultivibrator timing circuit for the generation of output waves ofuniform shape and amplitude in response to said pulses, saidmultivibrator circuit including capacitance for control of its timing,said multivibrator circuit also including adjustable grid biasing meansfor varying the period of said output waves to compensate for knowndifferences in the calculated traffic density of said highway and switchmeans to vary the capacitance of said timing circuit reciprocally inaccordance with the number of highway lanes being detected, an averagingcircuit having a specified time constant for receiving the output ofsaid timing circuit and for generating a voltage functionally related tothe period of and rate of receipt of said output waves, Va secondaveraging circuit having a specii fied time constant greater than thetime constant of said first averaging circuit for receiving the voltagegenerated by said first averaging circuit and generating a controlvoltage functionally related to the integral of said first voltage overa selected time period, a plurality of utilization device actuatingcircuits, and a control circuit capable of selectively actuating one ofsaid utilization circuits in accordance with the magnitude of saidcontrol voltage.

13. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform Wave form in response to randomexternal actuation, a timing circuit for the generation of output lwaves of uniform shape and amplitude and of predetermined period inresponse to said pulses, an averaging circuit having a specified timeconstant for receiving the output of said timing circuit and forgenerating a control voltage functionally related to the period of andrate of receipt of said output waves, and means for adjusting saidpredetermined period to vary the ratio of said control voltage to thepulse rate. t

14. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform wave form in response to randomexternal actuation, a timing circuit for the generation of output wavesof uniform shape and amplitude in response to said pulses, an averagingcircuit having a specified time constant for receiving the output ofsaid timing circuit and for generating a voltage functionally related tothe period of and rate of receipt of said output waves, and a secondaveraging circuit having a specified time constant greater than the timeconstant of said first averaging circuit for receiving the voltagegenerated by said first averaging circuit and generating a controlvoltage functionally related to the integral of said first voltage overa selected time period.

l5. A circuit of the character described, including a pulse generatingcircuit for producing pulses of uniform wave form in response to randomexternal actuation, a timing circuit for the generation of output wavesof uniform shape and amplitude and of adjustable period in response tosaid pulses, an averaging circuit having a specified time constant forreceiving the output of said timing circuit and for generating a voltagefunctionally related to the period of and rate of receipt of said outputwaves, and a second averaging circuit having` a specified time constantgreater than the time constant of said first averaging vcircuit forreceiving the voltage generated by saidV first averaging circuit andgenerating a control voltage functionally related to the integral ofsaid first voltage over a a selected time period.

16. A circuit of the character described including a pulse generatingcircuit capable of producing pulses of uniform wave form in response torandom external actuation, a timing'circuit for the generation of outputwaves of uniform shape and amplitude in response to said pulses and offrequency representative of the frequency of said pulses, and anaveraging circuit having a variable time constant for receiving theoutput of said timing circuit and for generating a control voltagefunctionally related to the period and rate of receipt of said outputwaves over a 'scale of magnitudes of said control voltage, saidaveraging circuit including means controlled by the frequency of saidoutput waves for varying said time constant in different respects forincreasing and decreasing frequency respectively. g

17. A circuit of the character described including a pulse generatingcircuit capable of producing pulses of uniform wave form in response torandom external actuation, a timing circuit for the generation of outputwaves of uniform shape and amplitude in response to said pulses, a firstaveraging circuit having a fixed time constant for receiving the outputof said timing circuit and for generating a voltage functionally relatedto the period of and rate of receipt of said output waves, a secondaveraging circuit having a variable time constant greater than the timeconstant of said first averaging circuit for receiving the voltagegenerated by said first averaging circuit and for generating a controlvoltage functionally related to the integral of said first voltage overa selected time period, said averaging circuit including meanslcontrolled by the relative output voltages of said averaging circuitsfor varying said variable time constant, a plurality of utilizationdevice actuating circuits, and a control circuitfor selectivelyactuating one of said utilization circuits in accordance with themagnitude of said control voltage.

18. A circuit for receiving random pulses produced by traffic passingone or more points in accordance with the rate Vof flow of trafiicthereby, including means for receiving said pulses, means forintegrating said pulses over an adjustable time period to derive anaverage pulse rate, means for indicating on a scale the pulse rate as sointegrated by said last named means, means for varying the ratio of theindicationon such scale to the rate of receipt of input pulses toaccommodate such scale to a wide range of rates of traffic flow andfurther means for varying the ratio of the indication on said scale tothe rate of receipt -of input pulses to compensate for the number ofsaid points connected to said receiving-means.

19. In a trac control apparatus-having a multiplicity of output circuitsfor controlling traffic in accordance with the rate of ow of traic perunit time, means for generating pulses from traffic passing one or morepoints, means for integrating such pulses by varying an electrical valuein one direction progressively therefrom and varying said electricalvalue in the opposite direction between pulses over a period of time toprovide an output voltage indicative of said integrated pulse rate andmeans for selectively operating one of said output circuits at a time inresponse to said voltage and in accordance with said voltage at suchtime.

20. An integrating circuit for averaging the duration and frequency ofrandom input pulses, said circuit including switch means actuated bysaid pulses for controlling the charging of a condenser, an averagingcircuit associated with said condenser to receive the output chargetherefrom and to integrate same over a given time period, and meanscontrolled by the output of said averaging circuit to vary the chargingrate of said condenser whereby the charge on said condenser will producean output from said averaging circuit having a linear relationship tothe duration and frequency of said random input pulses.

2l. An integrating circuit for averaging the duration and frequency ofrandom input pulses, said circuit including switch means actuated bysaid pulses for controlling the charging of a condenser, an averagingcircuit associated with said condenser to receive the output chargetherefrom and to integrate sarne over a given time period, and meanscontrolled by the output of said averaging circuit to vary the chargingrate of said condenser, said last .named means including a circuit forvarying the charging potential across said condenser, whereby the chargeon said condenser will produce an output from said averaging circuithaving a linear relationship to the duration and frequency of saidrandom input pulses.

22. In a traffic control apparatus, means for continuously accumulatinga quantity in response to traic elements passing one or more points,means for continuously progressively reducing such accumulation at apredetermined time rate, a multiplicity of output circuits forcontrolling trac appropriate to various levels over a scale of rates oftraic flow passing such point or points and means for selectivelyoperating the respective output cirvalues of such quantity, means forindividually adjusting the value for transfer from each of said outputcircuits to the next of said output circuits, and means interlocked withsaid last named means individually with respect to the transfer fromeach circuit to the next for individually adjusting the retransfer fromsaid next circuit to the preceding circuit to establish a greaterdifferential in value for the retransfer than for the initial transfer.

24. In a traffic indicating apparatus, input circuit means for receivingrandom pulses produced by traic passing one or more points, means forproducing an output electrical value substantially representative of theaverage rate of said pulses received over a time period, means forindicating on a scale such output value in terms of rate of traic ow,means for varying the ratio of such output value and scale indication tothe rate of pulses received, and means for adjusting such time period toprovide a range of time base values for such averaging and for inverselycorresponding rates of change of such output value and scale indication.

25. A combination as in claim 24, and including a multiplicity of outputcircuits corresponding to several segments of said scale of outputvalues respectively, and means for selectively actuating said outputcircuits in accordance with said output value.

26. A combination as in claim 24, and including a multiplicity of outputcircuits corresponding to several segments of said scale of outputvalues respectively, and means for selectively actuating at any one timethe one of said output circuits corresponding to any particular segmentof said scale in response to such output value being within a range ofvalues substantially corresponding to such particular segment atsubstantially such one time.

27. A combination as in claim 26, and said time period adjusting meansincluding two individually controllable adjusting means for setting suchtime period and means for selecting one ot' said two adjusting means forcontrol of such time period when said output value is increasing and forselecting the other of said two adjusting means for control of such timeperiod when said output value is decreasing, as a result of changinginput pulse rate.

References Cited in the tile of this patent UNITED STATES PATENTS1,593,993 Sprague July 27, 1926 1,823,739 Horton .r Sept. l5, 19311,944,723 Stirlen Jan. 23, 1934 2,170,160 Renshaw Aug. 22, 19392,176,742 La Pierre s Oct. 17, 1939 2,288,601 Barker July 7, 19422,295,534 Leathers Sept. l5, 1942 2,374,248 Tuttle Apr. 24, 19452,384,792 Brown Sept. 18, 1945 2,410,821 Hillman Nov. l2, 194642,448,113 Olafson Aug. 3l, 1948 2,506,368 Leonard May 2, 1950 2,594,276Barker et al Apr. 29, 1952 2,751,574 Jeffers June 19, 1956

